I assume Dick Smith is a store?
I got mine at Radio Shack, probably don't have them in your neck of the woods.
I like the analog ones, but digital is ok as well. The main purpose of them is to get all your speakers at the same Sound Presure Level in dB's by running test tones or your receivers pink noise in the setup menus. The auto setup in receivers does a pretty good job, but not sure it would work well to calibrate multiple subs.
I usually just go into the receivers setup menu and kick off the manual test tones and adjust all the speakers and subs to about 75-78dB's. With multiple subs, do them one at a time, then turn them both on...
Here is a good article on how to use a meter.
http://www.audiophilia.com/hardware/spl.htm
